Modern business requires vast amounts of printed material large quantities of which are produced by one-shot or single copy printing processes. For low speed applications typewriter-type printing terminals have adequate speed and for opposite end of the printing spectrum extremely high speed mechanical, xerographic and other special line printers are available.
In the intermediate speed range such as for telegraphic or facsimile receiving terminals, relatively low speed computer output terminal printers etc., a large variety of printers are available. Among the many types of printers in this area are ink jet printers, high speed occulting print ball printers and various types of printing processes utilizing specially coated papers. In this latter class of printing method some form of energy is caused to react with the specially coated paper in a predetermined area to make a visible mark. The form of energy applied is typically an electric current passing through the paper, some form of heat or thermal reaction induced in the paper or a photochemical reaction due to the impingement of some form of radiant energy on the paper surface.
It is to the coated paper printing systems and methods to which the present invention applies. An inherent problem with such coated paper printing systems is the paper or record receiving media itself. It requires the use of special papers which must be supplied by the manufacturer which of necessity limits the choice of a printing customer. The handling and inventory of such special papers is quite expensive. Probably the greatest disadvantage with special recording papers is their limited shelf life. Depending on the particular type of chemicals in the system being used they are usually very sensitive to humidity and temperature variations as well as the loss of sensitivity due simply to the aging of the chemicals forming the coating on the paper.
As a consequence, even though the marking systems utilized i.e., the passage of a current through a discrete area or the heating of a discrete area, etc., is usually quite simple and straightforward for such systems, the problems with the record receiving media, i.e., the coated paper has severely limited the acceptance of such printing systems in the business community.
What is needed in this particular technology is some means whereby conventional previously untreated paper could be satisfactorily used in the printing process so that such process would be competitive with other printing systems such as typewriter-type terminals, ink jet printing, xerographic printing systems and the like.
It has been found that greatly improved printing and/or recording is possible utilizing an energy absorbtive coating on the recording medium wherein the coating material is applied real time in-situ immediately prior to the printing operation. Utilizing the concepts of the present invention two or more different constituent materials may be nebulized and directly sprayed upon a sheet of paper or other suitable recording medium immediately prior to exposing said coating to an external energy source for the purpose of marking same. The instant printing system eliminates the problems of shelf life of precoated papers, it also allows the use of coatings which would have been impractical when shelf life was a consideration. It further allows a much greater latitude in the choice of paper to be used in the printing process.
The primary object of the present invention is to provide a coated paper printing system wherein the coating is formed real time immediately prior to the printing operation.
It is another object of the invention to provide such a printing system wherein the coating is formed from at least two separate constituent materials.
It is a still further object of the invention to provide such a printing system wherein problems of shelf life of the coated paper are eliminated.
It is yet another object of the invention to provide such a printing system which is adaptable for use with many different visible mark producing systems.
These and other objects, features and advantages of the invention will be apparent from the following description of the invention.